Crosscut samplers for dry material flowing under pneumatic pressure have not been unknown in the past.
Such a crosscut sampler is for the purpose of sampling the flow of dry particulate material flowing under pneumatic pressure in a flow duct, and in such a way that samples are taken at all different positions across the width of the stream of flowing materials in the duct. Such dry materials may flow with a unique characteristic in various types of ducts so that if the material flowing is not absolutely uniform, certain of the particles of certain sizes, or particles of certain density, may accumulate at one side or in one particular portion of the cross section of the flow duct; and unless a sample is acquired from all portions of the flowing stream of material, the sample may not be representative of the materials that are flowing.
In taking a crosscut sample of all of the materials flowing in the moving stream, numerous physical problems are encountered. Many of the dry materials which are carried in flow ducts under pneumatic pressure are extremely abrasive and any seals or bushings used in connection with a sampler are quickly eroded and deteriorated due to the continual abrading of the materials which are flowing. Depending on the design of the seals involved, certain of the types of materials which are being sampled will creep or migrate or be drawn into the seal, causing rapid deterioration.
Typical prior art includes U.S. Pat. No. 4,082,004 and 4,120,203.